Purification of anthraquinone



Petented Feb. 9, 1932 li ll bll) STATES PATENT OFFICE ALPHONS U. JAEGER, 0F GRr'AF'IDN, PENNSYLVANIA, ASSIGNOR TO THE SELDEN COIL SPANY, 01? IPITTEfBUBG-H, PENNE'YLVANIA, A CORPORATION OF DELAWARE PURIFICATION OF ANTHRAQUINONE No Drawing.

intention relates to the purification of we I *arpiinone, and more particularly to the purification of impure anthraouinone by catalytic processes.

5 rlnthraquinone, produced either by the cataly vapor phase oxidation of anthracen or, .,i:ially impure anthracenc, such as (l8 anthraccne. or by chemical oxidation ct anthrmzrme, containing numerous impuri 1o ties which render it unsuitable for the producti n of d tuii's and int rmediates, some of the impu res, e en when present in relatively small quantities, seriously affecting the shad of dyes produced. For this reason it ihle in the past to oxidize or semi-purified anthracene by catanor has it been feasible to attire which is not highly purito various forms: of chemical oxidations,

20 becausj is cost of renuwiug the undesirable rem the crude antiraquinone has vc, and in some cases no satisfacu'o c see have been available. It has refore been neces ary to use relatively "lily purified anthracene as a raw material the production of anthraquinone, thus greatly increasing the cost of the anthraquinone because most of the processes for purifyi crude anthracenc are relatively ex- 30 per 'i.

i be present process purifies crude anthraquiuone of v irious grades with high eificiency,

and results in a product of the highest purity which can be directly used without further :ation in the manufacture of dye stuffs,

crmits the production of products of )ly tine shades. According to the present invention impure anthraquinone is 'ljectcd to a vapor phase catalytic oxidai i the presence of contact masses which at tend to oxidize anthraquinone. It is ble by the p Went invention to compic y burn out the impurities present in the crude authraquinonc, or in some cases to rm them into products which are The l of anthraquinone is small,

y nil, and it is thus possible 10 present invention to transform crude ti .lu-aquinone into anthraquinone of the highest purity in a process which is cheap in Application filed August 15, 1928.

Serial No. 299,877,

its operating cost, and which gives most ex cellent yields of high quality product.

Two main classes of contact masses can be used in the present invention; lirstly contact masses which are capable of oxidizing the impurities present, usually transforming them by total combustion into carbon dioxide and Water, or fixed gases without having any considerable oxidizing effect on anthracene. These contact masses are known as anthracene purification contact masses, and are described in my co-pending application, Serial No. 228,977, filed October 26, 1927, and an of the contact masses there described may used in the present invention. Most of these contact masses, or more properly most of the preferred contact masses of this class, contain stabilizers; that is to say, non-catalytic compounds of the alkali metals, alkaline earth metals, and strongly basic earth metals.' The contact masses may also contain catalytically active components, which, however, are not specific oxidation catalysts, and which are designated in the above referred to application as stabilizer promoters. It should be understood that in the present application the terms stabilizers and stabilizer prometers are used in the same sense and in no other. Anthracene purification catalysts are the most elficient where the crude anthraquinone does not contain unoxidized anthacene, but where it may contain oily materials, phenanthrene derivatives, carbazole and other impurities which are present in crude anthracene and which are not completely removed in the oxidation to crude anthraquinone. The anthracene purification catalysts have substantially no oxidizing effect on anthraquinone under the reaction conditions described in my prior application above referred to. They are therefore highly eflicient in the process of the present invention, as they purify anthracene free, crude anthraquinone with a minimum of loss of anthraquinone or in some cases with substantially no loss atall.

Where the crude anthraquinone contains small amounts of anthracene it is normally not satisfactory to use an anthracene purification catalyst or contact mass, and in such thraquinone itself. Any such anthraquinone catalystmay be used in the present invention, but I have found that stabilized catalysts, such'as those described in my co-pending application, Seriall lor 196,393,1iled June 3,1927,nowPatent No. 1,709,588, dated April 23, 1929, are particularly effective, since they show good powers of oxidation for anthracene, and of destruction of impurities, while at the same time showing very low and in some cases no tendency to oxidize antl1raquinoner Highly effective contact masses particularly of'the stabilized type, are those in which base exchange bodies are contained, either non-silicious base exchange bodies or zeolites. Such contact masses are described in my co pending applications, Patent No. 1,694,122, dated December l, 1928, Patent No. 1,735,763, dated November 12, 1929, and Patent No. 1,722,297, dated July 30, 1929, and any such base exchange contact masses-which are suitable forthe' oxidation'of anthracene may be used. Contact masses containing leached base exchange bodies suitable for the oxidation ofanthraceneto anthraquinone are also highly effective for use in the present invention. Such contact masses are described in my co-pending application Serial No.

294,597, filed July 21, 1928, and any of these contact masses which are suitable for the oxidation of anthracene may be used in the pres ent invention." Contact masses containing base exchange bodies and suitable for the purification of anthracene are also extensively described in the anthracene purification application referred to above, and form some of the most eifectivecontact masses.-

While it is normally desirable to use an.- thracene purification catalysts or contact masses where the crude anthraquinone does not contain anthracene, it should be understood that such crude anthraquinones as well as anthraquinones containing small amounts of anthracene may be purified by the use of anthraquinone catalysts, and it shouldbe understood that such crude anthraquinones as well as anthraquinones containing small amounts of anthracene'may be purified by the use, of anthraquinone catalysts, and such processes are of course includedwithin the scope of the present invention. Ofcourse contact masses containing both anthracene purification and anthraquinone catalysts may be used. 7

It should be understood that the most effective anthracene purification contact masses and many of the highly effective anthraquinone catalysts or contact masses are alkaline; that is to say, contain anexcess of alkaline asopposed to neutral or acid stabilizers. For the present invention I prefer to use contact masses having an alkaline reaction, as many of the impurities present in the crude anthraquinone are relatively easily decomposed in the presence of an alkaline contact mass. This is particularly true of heterocyclic compounds which may be present and the alkaline contact masses also serve to decompose impurities of an organic acid.

'1 The reaction conditions under which the present invention is carried out will of course vary to a certain extent with the nature of the contact mass and with the chemical composition of the crude anthraquinone. In general the reaction conditions when using an anthracene purification catalyst are the same as when crude antliracenes are purified with the same contact mass that is to say, itis normally advantageous to operate with an excess of air, and to maintain such moderate temperatures as are described in detail in the examples in my prior application, Serial No. 228,977, filed October 26, 1927. Similarly when purifying crude anthraquinone with an anthraquinone catalyst, especially when the crude anthraquinone contains small amounts of anthracene as one of its impurities, the reaction conditions should be chosen similar to those for oxidizing high grade anthracene with the same contact mass, and the reaction conditions described in my prior applications above referred to may be effectively used in the process of the present invention.

It should be noted that the present invention puts crude anthraquinone on the same economic level as purified anthracene; that is to say, both of these products can be transformedinto' high grade anthraquinone with good yields by a single vapor phase catalytic oxidation. This standpoint should be borne in mind in. considering the relative efliciency of oxidizing crude anthracenes to crude anthraquinones which arethen purified by the present invention, and purifying the crude anthracene, for example, in accordance with my prior application, Serial No. 228,977, above referred to, or by effective solvent methods, for example, such as described inv my prior application, Patent No. 1,698,713,-

dated December 4:, 1928, and then oxidizing this purified anthracene to high grade anthraquinone in a single step, as described in some of the prior applications above referred to,

in a. Slll," step before oxidation.

" l e at lllft...llll may carried out by rape crude anthraquinone, preferably uniformly with an oxygen containing u; and passing it orer the catalysts above 'erred to, or crude anthrae so may be oxiliaed catalytic-ally to crude antln-aquinone, "nd the prod c necessary without separan from t 'e converter exhaust gases, may be i it er puriliel by the present inven- ..u some it is even desiral'xle to L the reac ion containing; the vaporcrude anthracene pass in series, first mass which produces crude en through a contact republic of p rilying the crude anthraone in accordance with the present inlon. I meter in most cases to carry out tl nroccss in two steps the react on con 4 as amcuint ct oxygen t mperaand the rite, are not lflliCt irily the for the onidaeion of crude ai'ithracene imthraquinone and lor the purificarude anthraquinone and by carrying process; in two separate steps, each be ca d out undc' the reaction ed for optimum results in a ticulur step. A further advantage yin out the production of high grade 'aquinone from crude anthracene in a 1 process lies in the fact that the XO- siting from the coi'nbustion of im- -om the oxidation of anthrauinone is usually very difewo steps, and frequently a or reaction conditions wi l 1 best suited for the conditions However, the cmnbination which crude anthraccne of variof purity is oxidized in a single high grade anthraquinone as descin ed re. In this connection it should be noted at throughout the present specification EtlljtlllftCOF; which are not sufficiently pure be oxidized directly to high grade in .ruquincne even with the best stabilized athrauuinouc contact masses in a single step will be consid red as crude anthracenes, al-

. h the decree of crudity and percentage iracene may vary within wide limits. .iile it is an a dvantag'c oi? the present inrention that it is possible to oitidize crude uinones, ei en anthraquinones conj large amounts of impurities directly grade anthraquinone in a single step, i V the crude zmthraquinone to a prelii'ninary purification, for example, by treatment with solvents,

either such as pyridine, or even more efi'ectivo furane solvents, such as furfural, or solvents which dissolve out phe anthrene but do not remove most of the carbazole, such as hydrocarbons of the benzene series, gasoline, acetone, alcohol, chlorinated solvents, such as orthodichlorbenzcne, chlorinated residues from the chlorine purification of light oils, etc. Such a preliminary solvent treatment is sometimes desirable, especially where the anthr quinone is very crude, as it reduces the amount of impurities to be burned out in a subsequent catalytic oxidation, which correspondingly decreases the exotherm, and particularly where an anthraquinone catalyst is used, decreases losses of anthraquinone. Thus for example, crude anthraquinone containing anthracene as well as other impurities may be subjected to a solvent treatment with future], resulting in an anthraquinone which contains anthracene as its main impurity. Such an anthraquinone can be very efllciently purified to high grade anthraquin one using a well toned anthraquinone catalyst. Such combined puritications are included within the scope ot the present m- Ewcmtple 1 Dark brown oily anthraquinone obtained by the catalytic oxidation of 2935% crude anthracene with a vanadium catalyst, and containing about 78.2% anthraquinone, substantially no unoxidized anthracenc, 445% carbazole, some phenanthrene, traces of phenanthraquinone, acid in'ipurities such as phthalic anhydride, benzoic acid, maleic acid, etc, can be purified by vaporizing uniformly into air in the proportion of about 1: 3:150 parts of air and then passing at 380-4t00 C. over a contact mass which is prepared by in timately mixing; 8.7 parts of Fe o with 87 parts of TiO in a mortar, suspending the mixture in 14-0 parts of water, adding 8 parts oi 100% KOH in the form of a 10 N KOH. solution, and then spraying onto 200 volumes oi pea sized pumice fragments which are agitated and heated sufficiently to instantaneously vaporize the water from the suspension as it sprayed onto them, Preferably the reaction is carried out in a converter provided with excellent teinperatiu'e control, such a tubular converter using a boiling; metal alloy bath, for example, alloys oi? mercury and cadmium, mercury and lead, and the like. the bath boiling at or a little below the rcaction temperature desired. The loading may be from 35 grams of crude anthraquinone per hour per 77400 c. c; of catalyst. Pracsuch as roughened quartz, silicates, minerals,

aluminum granules, artificial; carriers, formed, for example, from kieselguhr and water glass or kieselguhr and alkalies, such as-potassium or sodium hydroxides, carbonates or cyanides. The spraying should be carried out as described above. Other etlec tive contact masses may be prepared containing cobalt oxide, copper oxide, nickel oxide,

cerium oxide, titanium oxide, zirconium oxide, and the like, singly or in admixtures. Alkaline stabilizers, such as hydroxides, nitrates, cyanides, etc., of potassium are particularly efi'ective. Any of the other anthracene purification contact masses described in my application, Serial No. 228,977, above referred to, may be used.

--, E wample 2 Crude anthraquinone of various grades produced by the oxidation of various grades of crude anthracene with vanadium catalysts are washed with turtural or with phenanthrene solvents, such as benzol, toluol, solvent naphtha, acetone, gasoline, chlorbenzone, orthodichlorbenzene, or other chlorinated hydrocarbons, such as for example, residues from the chlorinepurification of light oils. Etarting with a crude ant-hraquinone containing from 7s to 80% of anthraquinone, a semi-purified anthraquinone of from 92 to 04% purity is obtained. The treatment may be by recrystallization or by leaching, and the 5 semi-purified anthraquinone can be eifectively purified in the presence of an anthracene purification catalyst prepared as follows:

18 parts of copper oxide prepared by precipitating a solution of copper nitrate of a strength corresponding to 17 parts of copper nitrate with 6 mols of water in 200 volumes of water, a solution of KOH being used. The precipitate caused is filtered and then suspended in 250 volumes of water to which are added 8 to 10 parts by weight of 100%' KOH, or a corresponding amount of KNOB or KCN. The suspension is then sprayed onto 200 volumes of pea sized pumice fragments, and the contact mass produced is calcined in a stream of air at 350 400 C. The semipurified anthraquinone described above is uniformly vaporized with air in the proportion of 1225-jparts by Weight, and is passed over the contact mass at 850-400 C.

' An anthraquinone is obtained whichis actually chemically pure. The loadings may be 41-5 grams of semi-purified anthraquinone per 7 7-100 0. c. of catalyst per hour. The exotherm evolved is not great, and converters using automatic reaction gas cooling, that is to say, a reaction gas cooling which increases in proportion to the increase in velocity of the reaction gases through the converter, may be used with excellent results. These converters are much cheaper than the bath type.

A semi-purified anthratpuinone'may also be obtained by Washing'IOO parts of oily tailings from the catalytic production of anthraquinone from crude anthraoene with 200 parts of a 10% NaOH solution, in order to remove acid compounds. The crude material contains about 80.36% anthraquinone. The semi-purified anthraquinone obtained can be purified'as described above, and yields substantially chemically pure anthraquinone with excellent yields.

Example 3 Crude anthraqu'inone having an anthraquincne content ranging from 6896% is obtained by the catalytic oxidation of different grades of anthracene. When 28-35% crude anthracene is oxidized the I anthraquinone may have a purity of 6884-%, and when semi-refined anthracene such as anthracene prepared by means of the phenanthrene solvents described in the foregoing example,

containing 68% anthracene is oxidized tained which is filtered by suction and washed free from the mother liquor. The cake obtained is then sludged with 35 parts of IK -SO, in 250 parts of water. 720 parts of 8-10 mesh quartz fragments are boiled in an alkaline potassium aluminate solution prepared by precipitating aluminum hydroxide from a solution of 112 parts of aluminum sule "late with 18 mols of water in 200 parts of water using concentrated ammonia and then dissolving the aluminum hydroxide after it has been filtered and carefully Washed in a solution containing 672 parts of 90% KOH together with 300 parts of water. The boiling is continued for three hours, whereupon the product is washed and treated with a hydrochloric acid solution until a methyl red indicator turns. The pretreated quartz which may of course also be substituted by pumice fragments, fragments of quartz filter stones, sand stones, Celite bricks, natural or artificial si icates, base exchanging or nonbase ciichaiu cspeciallv zeolites diluted ich in sili metal granules,

metal al- *anadium,

i, JllolOll of iron cobalt van- 4 fragments using heat ple l, and. the contact mass obtained is then blown with air at 4.00 C. for an hour or two.

Nichol, copper, silver. maiurancse and corium sa 1na replace part or all of the iron l and potassium nitrate, sodium um nit or other all-:aii or 1' 1 metal (1311133131111 ds may be need. i mass is filled into a tubular converter using a boiling mercury alloy bath 80% lead The tubes .y advan- -il: 1 diameter of 2 c. m. ll hcn 35% crude is umtcrmly porirzcd with air in the proportion 0;? l Eli-+ parts by weight an oily crude authraquinone of 73--78% purity is obta'tied. with a loading of 510 arr-no of crude anthrace e per tube per hour. 30 'lhe impurities are mainly pheuanthrene, 58-53% carbazolc and no amorucene. Under the same reaction condi ons semi-purified will ire a cruoe authraquinone x2. purity 111:, in a loading of l8 tube per ho nthrac ate pared as follow oh 5 mols of we of water, precipisolution, filtered and .ia .:s t water containing 8 ii 'lhe suspension is then volum s of pea sized pumice 'bed in the foregoing er;-

mass obtained blown hereunon it is filled or example, a conyci .c-r as described uinoue of about T lsifc described above, is uni- .rith air in the proportion ,ht and passed over rlnthraquim arcnce is obtained, loechst method. :orcticnl, based on the 1 a; d loadings of l-6 e per hour can be used. Crude s (385% can be readily I chore. two converters, in one of cccnc is oxidized to crude in the second the crude 7 "l l, a h .;h cgrade antely satisfactory for use as an intermediate for vat dyes can be prepared by carrying out the two steps described above in two catalyst layers in a single converter, the reaction gases first contacting with the anthraquinone catalyst for the manufacture of crude anthraquinoue and then with the anthraccne purification catalyst for the Fccamplc .4

Qrude authraquinone, prepared as described in lilxample 3, can be purified by means of an anthraquinone catalyst. This is erpecially effective where the crude anthraquinonc may contain some unchanged anthracene. It desired crude a-nthraquinone may be given a preliminary purification by washings, leaching or recrystallizing from solvents, such as furtural or phenanthrene solvents, as described in the foregoing examples. .2111 anthrau uinone contact mass suitable for t purpose is prepared with the following mixtures:

(1) 200 parts of a 83 B. potassium water glass solution diluted with 6-8 -volumes of water are mixed with a mixture of comminut ed silicates and kieselguhr until the suspension remains easily stirrable. The mixed diluentsz-i should preferably contain more than of lzieselguhr but the relative proportions may vary within wide limits.

(2) 18 parts of V 0 are reduced in a hot aqueous solution, acidified with H SO by means of sulfur dioxide, a solution of blue vanadyl sulfate being; obtained. The vanadyl sulfate 1' transformed into a brown solution of potassium vanadite, using just sufficient 10 N caustic potash solution.

(3) A, 540% manganous sulfate solution. isprepared. Suspension (1) and solution are poured together, and suflicient manganous sulfate solution is added in a thin stream with vigorous agitation until the reaction mixture eutid to phenolphthalein or just allraline. The mass solidifies to a dirty gel, which filtered with suction, slightly washed and dried, and constitutes a diluted zeolite contaiuin tetravalent vanadium and manganese in non-exchangeable form. Instead of suspending the diluent-s in solution (1) they may be suspended in solution (2), or solutions and (2) may be mixed and the diluents suspended in the mixture.

p "t or all of the potassium vanadite in fit) nitrates. If desirable the zeolites after drying, preferebly at 100 (3., may be subjected to base exchange after first hydrating by trickling water over the zeolite, or salt like bodies can be prepared'bycausing the zeolites to react with compounds containing suitable anions which are capable of reacting with the zeolites to form salt likebodies. The diluted zeolite contact mass described above may be used directly as an anthraquinone purification catalyst or may be heated to 420500 C. and then treated with 3-5 burner gases.

Crude anthraquinone containing 66.28% anthraquinone, 14.34% anthracene and 2.5% carbazole, or a crude anthraquinone containing 69.8% ant-hraquinone, 8.13% anthracene, and 1.58% carbazole, or finally a crude anthraquinone containing 92.05% anthraqumone, no anthracene and 0.62% carbazole canbe vaporized with air in the proportion of 1: 35 partsby weight and passed over the contact mass at 390400 C. All of the crude anthraquinones above described yield anthraquinones of excellent appearance, small amounts of phthalic anhydride being encountered in the tailings. The yields based on anthraquinone content range between and of theory.

Example 5 144 parts of V 0 are suspendedin 200 parts of water to form a slurry, and after wvarming to (SO-70 C. are dissolved with 42 volumes of 10 N. KOH. 14.8 parts of manganous sulfate and 2 'mols of water are dissolved in parts of water and the solution cipitate which forms is filtered, thoroughly washed with water, and suspended in a solution containing '10 parts of potassium" bromide in 200 parts of water. The suspension is then sprayed onto 400 volumes of pea sized pumice fragments to produce a uniform coating, as described in the foregoing examples. The stabilized contact mass thus obtained is filled into a converter. and vapors crude anthraquinone containing 88'90% anthraquinone, and 12% carbazole admixed with air in the proportion of 1:25 by weight are passed over the contact mass at 380-420 C. A' high grade anthraquinone is obtained which is Y very suitable as a dye stuff intermediate and analyzes 99.8% pure by the Hoechst method.

Similar results may be obtained by using the vanadates of iron, cobalt, nickel, titanium, aluminum, copper, silver, lead or other metals instead of manganous vanadate.

Other stabilizers such as potassium nitrite,

. potassium nitrate, potassium cyanide, potassium chloride, potassium fluoride, potassium acid floride, potassium sulfate,'potass1um b1- su'lfate, sodium hydrogen phosphate, potas sium hydroxide, sodium carbonate, and the V like'm'ay be used in various quantities, depending on their efficiency as stabilizers.

Instead of using vanadium other metal elements of the fifth and sixth groups of the periodicsystem may be used, such as molybdenum, tungsten, etc. Mixtures of two or more metal elements of the fifth and sixth groups may also be used.

Example 6 30 kg. of 38 potassium waterglass are dilutedwith 300 liters of water and mixed with a solution containing 6.75 kg. of ferric chloride in 225 liters of water, the mixture takkali'ne to phenolphthalein. The precipitate i which forms is separated from the liquid by decantation or filtration and is pressed and dried in the air or at temperatures below 100 C. The product may then be broken into pea sized fragments.

The ferric chloride may be substituted partly or'wholly by other iron salts, such as ferric sulfate, ferrous sulfate, ferric nitrate, ferrous acetate, and the like or corresponding salts of copper, cobalt, or nickel.

The contact masses constitute two-component zeolites being the reaction products of twov typesof components, namely, a soluble silicate and a metal salt. They are excellent contact masses for the purification of crude anthraquinone and, if. desired, their catalytic efficiency can be further increased by embedding diluents into the zeolite structure, such as, for example, oxides or other compounds of iron, cobalt, nickel, copper or a plurality of them. TiO ZrO ThO ZnO, and CdO may also be present if desired.

Similar zeolite contact masses are obtained by adding a solution of potassium aluminat-e to the precipitate with vigorous agitation.

The potassium aluminate solution should be prepared bymixing a solution containing 9.9 kg. of crystallized aluminum chloride with a solution of potassium hydroxide until the aluminum hydroxide which at first precipi tates has again dissolved. After settling, the undissolved residue is separated from the liquid, pressed and dried at temperatures under 100 C. whereupon it isbroken into suitable fragments. Metallates or other amphoteric metal oxides may be substituted for the These contact masses, especial-v aluminate. lywhen containing cobalt, are well suited for the purification of crude anthraquinone.

Twwcomponent zeolites may also be prepared by causing soluble silicates to react with metallates instead of metal salts or three-component zeolites can be prepared which are the reaction product of soluble silicates with both metallates and metal salts.

Examples of metallates which may beused are potassium aluminate, potassium chrounte, sodium plumbite, potasslum zmcate,

I c: an to. ail salts of the heavy 1netsucl iron, cobalt, nickel, copper, and

1' may be used as the metal salt components.

Zeollte (intact masses may also be treated 1h suit solutions to introduce other by base exchange. Thus, for exan'iple, .:ontaining the elements iron, cobalt, copper, chromium, vanadium, lead,

silver may be introduced by trick- "e corresponding salt solutions over the t l zeolites, the solutions being prefer- 1r o1 IP)? strength.

'l hc zeolites may also be caused to react "l1 cempouinls containing anions capable f forming slt-lilze bodies With the zeolites. '1 compounds are those conthe metal acids of the fifth "'l'tfilpii of the periodic system, such :id. n'iolybdic acid, tungstic acid, acid. chromic acid, etc. The nitrate, chloride, sulfate, or phosphate anions may also be used.

Other t pes of zeolites may be utilized when they contain or are associated With suitable l tic elements Which may be present as partor the complex molecule of the zeolite or may be embedded in the orm of diluents in ace xy Wet or fusion methods.

.iich do not have base er:-

such as polysilicates of iron, 5, copper, aluminum, chromium, eslyl silicate, etc. when stabilized v .1 conipoiu'ids of the alkali or alkaline tals, such as KGN, KNQQ, K1793, i phosphates, @aO. NaCll and the 40 ll in t e formation of the silicates the reaction n'iixture may be maintained sullici- 5' near to neutrality to litmus so that compounds are. present. uother example of the three-component ."(l to above is prepared folof crystallized aluminum sulfate are 1 in 10 liters of Water and suflicient i on is add d until a potassunn r... ill i ate solution obtained. which then poured llltO a solution oi: 20 kg. of 38 De. I. lass diluted with 300 liters upon a 10% solution oi: oi cobalt and ferric nitrates in the ratio of arts coba t nitrate to one part ferric purity, for example a crude anthraquinone of 74.4% purity, freed from unoxidised anthracene is uniformly vaporized into air stream at the ratio of 1 part crude anthraquinone to 30 parts of air and passed over any 1 Example '7 Very effective contact masses for the purification of crude anthraquinone are obtained by using alkaline reacting contact mass co1npositions containing one or more metal elements of thel'ifth and sixth groups of the periodic system, such as vanadium, tantalum, chromirnn, molybdenum, tungsten, or uranium. Such contact mass can be prepared as follows:

182 parts of very pure V 0 are dissolved in 250 parts of a KOH solution containing 22.6 parts of 100% KOH. Tbereupon a solution containing 18.8 parts of ferric sulfate and 18.8 parts of copper sulfate With 7 mols of Water dissolved in 300 parts of hot Water is prepared and the vanadalie solution is poured into it before it is cooled, vigorous agitation being maintained throughout the mixture. The precipitate obtained filtered by suction Washed free from the mother liquor and sludoged With 15-20 parts of KOH in 250 parts of Water. ed onto 500 volumes of pumice fragments from 8 to 12 mesh.

M00 V03 or a mixture may replace part or all of the V O and one or more salts of nickel, copper, silver, manganese or cerium may replace the iron and copper used. Instead of KOH as a stabilizer. it may be partly or Wholly replaced by KCN, NaOH, CaOH or other alkaline compounds containing; alkali or alkaline earth metals. Alkali metal metallates. such as potassium eluminate. cadmiate or chromite are also effective stabilizers: in such cases the amphoteric elements, such as aluminum, play the part of stabilizer promoter. lust-cad of using; pumice fragments, other carrier materials may be used, such as fragments of quartz, quartz filter stones, sand stones, Gelite bricks. transients of natural or artificial silicates, base exchange bodies especially Zeolites diluted with materials rich in silica, metals such as aluminum granules, metal alloys such as ferrosilicon, ferrmanadium, ferrochromc, and the like; preferably the surface of th a carrier materials should be roughened r: etch l The crude anthraquinone is purif ed by means of the above contact was; midnireaction conditions described in the foregoing' examples.

This suspension is then coat- E sample 8 A contact mass is prepared by dissolving 375 parts of aluminum nitrate with 9 mols of water in water to form a 20% solution, which is then transformed into the corresponding potassium aluminate solution using sufficient 10 N. KOH so that av 10% excess remains. A 20% solution of a mixture of ferric nitrate, cobalt nitrate and copper nitrate in the ratio of 2:8: 1 is poured into the aluminate solution until the reaction mixture remains neutral or slightly alkaline to phenolphthalein. The resulting precipitate is filtered-off and dried and is a non-silicious base exchange body. Diluted non-silicious base exchange bodies can also be preparedby incorporating diluents such as iron ores, cobalt ores, copper ores or inactive diluents such as kieselguhr, Celite brick refuse, glaucosil (the acid leached residue of green sand), etc. It is also possible to add to the metallates 35% of complex compounds, such as a blue onprammonium compound obtained by dissolving basic copper carbonate in an ammonia solution.v Other metals may be introduced by base exchange or salt-like bodies can be prepared.

Where the crude anthraquinone to be purified does not contain unoxidized anthracene, the contact mass mayadvantageously be freed from metal elements of the fifth and sixth groups of the periodic system but where the crude anthraquinone contains unoxidized anthracene in smaller or greater amounts, the contact masses used should be anthraquinone contact masses, that is to say should preferably contain metal elements of the fifth and sixth groups of the periodic systemwith Or without other elements. Such contact masses, which favor the oxidation of anthracene to anthraquinone, are described in my A combined contact mass which contains both anthracene purification and anthracene oxidation components may be prepared as follows r 18.2 parts of V 0 are dissolved in 250 parts of KOH solution containing 22.6 parts of 100% KOH, forming potassium vanadate. 27 parts of ferric sulfate are dissolved in .300

orous agitation. The precipitateobtained is filtered by suction, washed free from the mother liquor with water until the wash water is colorless and then the wet cake is sludged with 250 parts of water and 28 parts of potassium sulfate are dissolved in the suspension. The above component is an anthracene oxidation component and an anthracene purification component is prepared by dissolving 47 parts of cobalt nitrate with six mols ofwater in 200 parts ofwater and precipitating the cobalt hydroxide with sufficient 5 N. KOH solution. The precipitate is filtered, washedfree from the mother liquor, and suspended in 300 parts of water, to which 8 parts of KOH are added. The two suspensions are poured together, intimately mixed and coated onto 700 volumes of 8l2 mesh pumice fragments as described in some of the foregoing examples. The mass is then blown with air and filled into a converter. Crude anthraquinone of -82% purity containing 343% carbazole is uniformly vaporized with air in the proportion of 1:35 and passed over the contact mass at 370420 C. A high grade anthraquinone results which analyzes 99.9% purity by the Hoechst method and is well suited for dyestuff intermediates. V

With the contact mass, crude anthraquinone can be purified when it contains more or less unoxidized anthracene. Insuch a case, not only are the impurities burned to fixed gases but the unoxidized anthracene is transformed to anthraquinone at the same time. Similar results are obtained when the contact mass is varied, for example, by varying the amounts of ferric sulfate used, which can be within fairly wide limits or by replacing part or all of the ferric sulfate with various amounts of other salt solutions, such as solutions of salts or manganese, cobalt, nickel,

copper, silver, magnesium, titanium, cerium or a mixture. The amount of K SO, 1n the suspension may also be varied within wide plex, such as, for'example, KCN, K CO NaGH, Ca(OH). and the like. If desired a mixture of alkaline stabilizers may be used.

This application is in part a continuation of my co-pending applications Serial No. 228,977, filed October 26, 1927, Patent No.

1,694,122, dated Dec. 4., 1928, Patent No. 1,709,583, dated April 23, 1929, Patent No. 1,735,763, dated November 12, 1929, Patent No. 1,722,297, dated July 30, 1929, and Serial No. 29%,597, filed July 21, 1928.

in the claims the expression alkali forming metal is used to cover the alkali metals and the alkaline earth metals and this expression will have no other meaning in the claims.

What is claimed as new is:

1. A method oi purifying crude anthraquinone, which comprises subjecting it in the vapor phase and in the presence of an oxygencontaining gas to the action of a contact mass containing a vapor phase oxidation catalyst, damped with an amount of a compound of an alkali forn'iing metal suiiicient to bring the activity of the oxidation catalyst below the level at which substantial oxidation of anthraquinone takes place.

2. A method of purifying crude catalytic anthraquinone obtained by the catalytic vapor phase air-oxidation oi impure anthracene, which comprises subjecting it in the vapor phase and in the presence of an oxygencontaining gas to the action of a contact mass containing a vapor phase oxidation catalyst, damped with an amount of a compound of an alkali forming metal suilicient to bring the activity of the oxidation catalyst below the level at which substantial oxidation of anthraquinone takes place.

3. A method of purifying crude catalytic anthraquinone obtained by the catalytic Vapor phase air-oxidation of crude anthracene, which comprises subjecting it in the vapor phase and in the presence of an oxygen-containing gas to the action of a contact mass containing a vapor phase oxidation catalyst,

damped with an amount of a compound of damped with an amount 01 a compound of an alkali metal suificient to bring the activity of the oxidation catalyst below the level at which substantial oxidation of anthraquinone takes place.

5. A method of purifying crude catalytic anthraquinone obtained by the catalytic vapor phase air-oxidation of impure anthracene, which comprises subjecting it in the vapor phase and in the presence of an oxygen containing gas to the action ot a contact mass containing a vapor phase oxidation catalyst, damped with an amount of a compound oi an alkali metal suificient to bring the ac- 6 tivity of the oxidation catalyst below the level at which substantial oxidation of anthraquinone takes place.

6. A method of purifying crude catalytic anthraquinone obtained by the catalytic vapor phase air oxidation of crude anthracene, which comprises subjecting it in the vapor phase and in the presence of an oxygen-containing gas to the action of a contact mass containing a vapor phase oxidation catalyst, damped with an amount of a compound of an alkali metal sutficient to bring the activity of the oxidation catalyst below the level at which substantial oxidation of anthraquinone takes place.

7. A method according to claim 4, in which the compound of the alkali metal is strongly alkaline.

8. A method according to claim 5, in which the compound of the alkali metal is strongly alkaline.

9. A method according to claim 6, in which the compound of the alkali metal is strong ly alkaline.

10. A method according to claim 1, in which the contact mass contains in addition to the vapor phase oxidation catalyst and the compound of the alkali forming metal at least one catalyst for a vapor phase reaction other than oxidation.

11.. A method according to claim 1, in which the contact mass contains vanadium.

12. A method according to claim 2, in which the contact mass contains vanadium.

13. A method according to claim 1, in which the contact mass contains at least one base exchange body.

14. A method of transforming impure anthracene into high-grade anthraquinone, which comprises subjecting the anthracene to vapor phase catalytic oxidation inthepresence ofavaporphaseoxidation catalyst for anthracene and subjecting the crude anthraquinone thus produced Without separation of impurities to the vapor phase catalytic oxidation in the presence of an oxygen containing gas and of a vapor phase oxidation catalyst damped with an amount of a compound of an alkali forming metal sufficient to bring its activity below the level at which substantial oxidation of anthraquinone takes place.

Signed at Pittsburgh, Pennsylvania, this 13th day of August, 1928.

ALPHONS O. J AEGER. 

